It's worth noting that there was a time when both Lindback and Markstrom were considered can't miss goaltending prospects. If you go back a couple of years, you'll also recall that the hockey world had Malcolm Subban's name etched on the Vezina multiple times already. Goalie prospects seem to rise and fall faster than boy bands.
I'll admit to being a big Lehner fan boy as recently as a year ago. My sense, though, is that the team has soured on him as much for character issues as anything else. Rumblings are that he is not the most popular guy in the room, hence the reason why players were so quick to praise and embrace Hammond. ("Hey, a goalie who isn't surly and remote all the time!") Obviously Lehner has a ton of athleticism and potential, and trading him does have the potential to come back and bite us, but there's also a good chance that he ends up as just another guy who flashed talent but couldn't deliver consistently.